Recently, the environment has become of major interest, and various studies about the reuse of resources have been made. Regarding non-crosslinked cured materials such as plastics, etc., a method has been known for reusing them after decomposition. However, there have never been known a method for reusing a three-dimensional crosslinked polymer, particularly cured coating film:
In Japanese Laid-Open Patent Publication No. 5-96231, there is disclosed a method for stripping a coat applied on a plastic molded article and a coat stripping agent. However, there is no description of the reuse of the stripped coat.
On the other hand, the present inventors have intensively studied (meth)acryloyl isocyanates and derivatives therefrom as well as polymers obtained from them (e.g. Japanese Laid-Open Patent Publication Nos. 60-231642, 61-272207 and 63-46207 corresponding U.S. Pat. Nos. 4,935,413, 4,788,256 and 4,816,537). They have also studied curable coating compositions based on reaction with a polyol compound, in view of the reactivity of an acyl isocyanate group or a substituted acyl isocyanate group contained in the polymer, and cured materials obtained from the compositions. Also, it has been found that the acyl carbamate bonds, which are formed by a reaction of acyl isocyanate group or substituted acyl isocyanate group with alcohol, easily proceed alcohol-substituting reaction by heating in the presence of alcohol.